For optical measurements at different wavelengths, thus, for example, in the case of a spectrometer, one requires either a composable light source for transmitting light and a broadband receiver or a broadband light source for transmitting light and a decomposition of the light into its spectral fractions at the receiver. Here, only the first case will be considered.
“Light” in the sense of this invention is not limited to the visible range of the electromagnetic spectrum, but, instead, can be any wavelength or set of wavelengths, especially also wavelengths of the far ultraviolet (UV) and wavelengths lying in the infrared (IR) range.
Usual embodiments of a composable light source involve, for instance, a broadband light source coupled with a dispersing element (e.g. a prism or an optical grating) or a set of narrowband, individual light sources (e.g. LEDs).
In both cases, light beams of different wavelengths emerge in different directions. If a certain direction, for instance, exactly toward the receiver, is desired, then the light beams must be merged either via a mechanical movement (e.g. a rotation of the grating) or via a fixed optical arrangement (e.g. a semi-transmissive mirror).